Aeronautical propeller



Flo $29,192; I 1351,15'2

, E A-REED AERONA U I QAL PRoPEppER Filed April 28. 1925 W 4%22 BY ATTORNEY Patented Nov. 29, 1927. v

UNITED STATES 1,651,152 PATENT OFFICE.

SYLVANUS ALBERT REED, OF NEW YORK, N. Y., ASSIGNOR TO THE RE ED PROPELLER GO. INC.,'OF NEW YORK, N. Y., A. CORPQRATION OF NEW YORK.

AERONAUTICAL PROPELLER.

Application filed April 28, 1925. Serial No. 26,353.

My invention relates generallyto aeronautical propellers and more partlcularly to those of the metal type. I have herein shown my present improvem'entsas embodied in oneforni of my improved type of propeller made preferably in one piece of light weight metal, having high tensile properties, such for example as duralumin, and where the solid, knife-like blades have such thinness as to be obliged to rely to an essential degree upon centrifugal force for the necessary rigidity, while having such adjustment and gradation of sections, that the inherent rigidity of the material suiiices to maintain constancy of pitch.

In such propellers, when it is desirable for economy to make them interchangeable with wooden propellers on the same steel hub, certain means have'been devised involvingthe provision of a flattened portion, or with a warped flattening at the center, and with filler-blocks to accommodate the customary hub-flanges and bolts, which arrangement detracts somewhat from the propulsive efi'ect of the parts of the blades close to the hub.

\Vhen it is possible to supply such propellers with their own hubs, a simplification in structure and a reduction of weight has resulted, and I have invented a further simplification which reduces the weight of both propeller and hub and aifords at the same time blades having propulsive power quite up to the hub itself. v

My invention is especially useful in making it possible to fabricate a propeller from a metal plate produced by ordinary rolling mill process, without special forging at the propeller center, for the purpose heretofore 40 of providing an enlargement of width through which could be drilled a hole for the engine shaft.

Stated'somewhat specifically, my invention consists substantially in making a contral slot through a comparatively th1nel0ngated metal plate at the center of its length from edge to edge and in the plane'of the plate, and then enlarging the width of this slot by wedging until it is of suflicient width to admit the driving extension ofthe engine shaft, or. a sleeve-like liner which may fit or be keyed on said shaft. The invention also includes a,liner or hub-sleeve with lateral fins or side extensions adapted to fill more or less such widened tapering slot extensions and thereby increase the radius of torque stress transmission, and it further may include clamping transverse reinforcing means to secure the propeller firmly to the driv; mg means. and to counteract any splitting tendency at the tapering ends of the slot. My invention also includes the peculiar method which I employ in making these metal propellers, all of which is more fully set forth in the following description and particularly pointed out in the claims. l have illustrated a type of my invention inthe accompanying drawings, wherein;

Fig. 1, shows aside elevation of my improved propeller in flat partly formed condition, the central slot being indicated in dotted lines.

big. 2, shows an edge view of the same and looking at one end of the slot.

Fig. 3, is a similar view to that of Fig. 2, but with the central slot enlarged laterally.

Fig. &, is a perspective View of the propeller formed from the fiat body by twisting the same, together with a sleeve or hubbolted in place in the enlarged central aperture.

Figs. 5, 6 and 7, show the hub or sleeve detached and in side, top-plan and end views, respectively.

Fig. 8, is an enlarged perspective View of the central part of the propeller with the hub and the exterior reinforcing pieces for the same.

Referring to the drawings, Figs. 1 and 2, show a one-piece metal propeller 1, having blades 2 and 3, with a. central blade-connecting part l, and with the parts in flat condition before being twisted or bent into finished form. "lhis flat plate 'or piece 1, is preferably in annealed condition and made of wrought metal or alloy of light weight having high tensile strength, for example duralumin, and the blades are formed to the contour surfaces requisite for an aeronautical propeller, and in accordance with my improved type of propeller, the blades taper in thickness and have; their outer portions so-thin as to require reliance to a substantial degree upon centrifugal force for the necessary rigidity to resist torque and thrust stresses without undue deflection, and yet having such adjustment of dimensions as to maintain constancy of pitch during flying service. The center part 4:, is comparatively wide and thin and obtains the maximum thickness. a convenient thickness at such'part being one and one-half inches, while near the blade tips the thinness may reach threesixteenths of an inch. A slot 5,,is formed at the center of part 4, and extends through the.

same from edge to edge thereof in the plane of the same, with the elongation of the slot extending in the direction of the blades and about sixteen inches in length, though these dimensions may be varied as found expedient. This slot is then ex anded lateral] by suitable wedging tools to a considerable width, say about three and a quarter inches maximum, and tapering to nothing at the extremities of the slot towards the blades, thereby forming a slitted eye or opening 6, expanded for the driving connection, but without an appreciable stretching of the metal, though there is a slight shortening of the length of the entire structure measured from tip to tip, as indicated in Fig. 3.

The propeller is then twisted so as to give the blades appropriate pitch-angles diminishing helically towards and to the tips, the twist being continuousin one direction from tip to tip. This twist around the longitudinal axis of the propeller in one direction results in the leading edge of each blade crossing 'over the axial line to become the leading edge of the other, and the trailing edges likewise crossing over, while both camber faces are disposed upon the same side, namely, the forward side of the twisted propeller. The propeller is then heat treated.

The expanded eye 6, in the twistingoperation has its tapering opposite ends displaced in reversely oblique directions and a steel hub 7, bored with a central hole 8, to lit the engine-shaft extension 9, and keyed thereto by means of key-way 10, is provided with oppositely extending has or projections 11, 11, constructed with oblique twist to opposite angles in order to fit the oblique disposition of the tapering ends of the eye 6. This hub is fitted snugly within the eye or aperture 6, without'play between the pa ts and the fins may be provided with bolt-holes 12, 12, which register with similar boltholes 13, 13, in the side walls of the expanded-eye, for the reception of securing bolts 14, which are passed through the registering bolt-holes and serve to firmly secure the hub and propeller together, the bolts being provided with washers 15. As a reinforcmg means, I may-also use the rigid metal pieces or bars 16, which are placed against the exterior surface of said central part, opposite-each other and are pierced by the bolts 14, which'also serve to clamp said pieces firmly against thesides of the propeller and thereby aid in solidifying the assemblage of said parts. The hub may be lightened by drilling holes in it or removing otherparts of the body of metal which can be spared without impairing the strength of the hub for the required service. If preferred, instead of fitting the hub 7, to the shape of the expanded eye 6, the latter may be lilled with any appropriate material, either molten or solid, and the filling then drilled through the center for the reception of the drive-shaft or for a steel shaftrcceiving sleeve, the latter being keyed to both the filling and the shaft.

In cases where it is desirable to accommodate the width of the central part 4, of the propeller where the hub is located, to a certain length of huh, I accomplish this by slightly contract-ing the width, as indicated in Fig. 1. For example, the width at such place may be eight inches to accommodate a hub of that length, while the wider portions of the propeller beyond such contraction may be nine or ten inches in width.

Another important advantage derived' trom this construction and arrangement of metal propeller is that propellers may be made from metal plat-es produced by ordinary rolling mill processes and the more expensive work of special forging thereby avoided.

I wish to be understood as not limiting my invention to the exact constructions herein shown. as it is manifest'that various modifications may he made in the different parts thereof. without, however, departng from the spirit ot'the invention.

Having thus described my invention, what I claim and desire to secure by Letters Patent is;

1. An aeronautical propeller made of a single plate of metal having substantially the physical properties of light-weight metal alloys of high tensile strength, such for example as duralumin, the propeller blades being twisted to pitch-angles decreasinghelically from roots to tips and tapering in thickness towards the tips to such a'degree of thinness that without the effect of centrifugal force they would deflectunder service thrust to an unserviceable degree, and having also sufficient inherent rigidity to maintain in service suflicientconstancy of pitch, the central part of said propeller being eye.

rigidity derived from centrifugal force, thecentral part of said propeller being comparatively wide and provided with a central expanded-eye extending through said part from edge to edge and elongated in the direction of said blades, and a drivi-ng-member provided with lateral fins fitting in said 4, An aeronautical propeller having a blade-supporting central part made from metal relatively thin and comparatively wide in a plane including or parallel with the rotational axis and formed with a central elongated aperture extending through it in the direction of its width, for receiving a driving-member.

5. An aeronautical propeller having a blade-supporting central part made from a relatively thin and wide piece of wrought metal and having an expanded slitted-eye extending width-Wise of said part from edge to edge thereof, for receiving a driving-member.

6. An aeronautical propeller made from a single piece of metal having its central part formed in a plane including or parallel with the rotational axis, said part being provided with an elongated aperture extending through it in the direction of said plane, for connecting the propeller with a driving member.

7 An aeronautical propellermade from a single piece of metal having its central part formed in a plane including or' parallel with the rotational axis, said part being provided with an opening extending through it in the direction of said plane and laterally elongated in said direction, and a drivingmember provided with lateral extensions fitting said opening and the lateral elongations thereof.

8. An aeronautical propeller made from a single piece of metal having its central blade-connecting part in a plane including or parallel with the rotational axis, said part being provided with an opening extending through it in the direction of said plane and laterally elongated in said direction, driving means provided with lateral fins fitting said opening and the lateral elongations thereof, and securing bolts passing through said part and the respective fins of the drivmg means. I

9. An aeronautical propeller made from a single piece of metal having its central blade-connecting part formed comparative- 1y wide in a plane including or parallel with t 1e rotational axis, said part being provided with an opening extending through it in the direction of its width and laterally elongated in the direction of the blades, driving means provided with lateral fins fittingv said opening and the lateral extensions thereof,

securing bolts passing through said part and the respective fins of the driving means, and reinforcing pieces secured against the exterior sides of said part by means of said bolts.

10. An aeronautical propeller made from a single piece of metal having its central blade connecting part formed comparatively wide in the plane including or parallel with the rotational axis, said part being provided with an opening extending through it in the direction of its width and elongated laterally in the direction of the blades, driving means provided with lateral fins fitting said opening and the lateral extensions thereof, and means for reinforcing the ends of the elongated opening.

In testimony whereof, have hereunto set my hand.

SYLVANUS ALBERT REED. 

